1. Field of the Invention
The present invention is generally related to a marine propeller and, more particularly, to a marine propeller that is provided with one or more vents which aerate the blades of the propeller at a rate which is an inverse function of the rotational speed of the propeller.
2. Description of the Related Art
U.S. Pat. No. 3,754,837, which issued to Schimanckas on Aug. 28, 1973, describes a variably ventilated propeller. A propulsion device comprises a propeller shaft supported by a lower unit and extending rearwardly through an exhaust gas opening in the lower unit, a propeller having a hub adapter for discharging exhaust gas therethrough and mounted on the rearwardly extending propeller shaft for common rotary movement with the propeller shaft and for axial movement relative to the propeller shaft between a first, forwardly located position and a second position located rearwardly of the forward position with a propeller spaced axially rearwardly of the lower unit exhaust gas opening. It also comprises means for biasing the propeller toward the rearward position.
U.S. Pat. No. 4,545,771, which issued to Iio on Oct. 8, 1985, describes a propeller and exhaust system for an outboard motor. The performance is improved by permitting the flow of some exhaust gases in proximity to the propeller blades at low speeds so as to aerate this area and so as to preclude the aeration when the speed of the propeller exceeds a predetermined speed for improving thrust.
U.S. Pat. No. 4,802,872, which issued to Stanton on Feb. 7, 1989, describes a regulated aeration of gases exhausting through a propeller. Aeration holes defined by an outer propeller hub include closure devices which seal the aeration holes during rotation of the propeller due to centrifugal forces in a predetermined speed of rotation range. The aeration holes provide high power at low boat speeds and are sealed at high boat speeds to avoid further aeration and loss of forward thrust. The speed of rotation at which the aeration holes are sealed is adjustable.
U.S. Pat. No. 5,916,003, which issued to Masini et al. on Jun. 29, 1999, discloses a propeller vent plug with fluid passage. A propeller device is provided with vent apertures and plugs which fit into the vent apertures to be retained in position during use of the propeller device. The vent plugs are provided with openings therethrough so that fluids can flow from a region within a hub of the propeller device to a region proximate the outer cylindrical surface of the hub. The fluids flowing from the internal portion of the hub flow towards regions of low pressure near the propellers. The plugs can be changed to modify the size of the ventilation aperture without having to change the propeller device itself. One embodiment of the plug is provided with a movable cover that closes the opening progressively in response to increasing rotational speed of the propeller device.
U.S. Pat. No. 6,375,528, which issued to Neisen on Apr. 23, 2002, describes adjustable variable vent opening plugs for engine exhaust. The plug includes a main body configured to be secured within an opening in a wall of a gear case in flow communication with an exhaust passageway through the gear case. The vent plug main body includes a flow passage therethrough and a planar flow restriction member extends across the flow passage that includes an opening. The main body also includes a variable flow restriction member chamber having an annual groove extending around the chamber. A variable flow restriction member is located within the chamber and includes an opening having the same diameter as the diameter of the opening in the flow restriction member. The variable flow restriction chamber is movable within the chamber groove to adjust an amount of exhaust passing through the openings of the flow restriction member and the variable flow restriction member.
U.S. Pat. No. 7,056,091, which issued to Powers on Jun. 6, 2006, describes a propeller hub assembly having overlap zone with optional removable exhaust ring and sized ventilation plugs. A propeller hub assembly is provided with a through hub exhaust propeller hub characterized by an interior overlap zone defined by the composite interior dimensions of a selected number of conventional propeller hubs and optionally fitted with removable exhaust ring and/or sized ventilation plugs. The hub assembly of this invention includes specially designed driver adapters for insertion in the overlap zone of a universal propeller hub and accommodating corresponding conventional OEM factory thrust washers normally used in the conventional propeller hubs.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.